Most electronic systems today include one or more electronic circuits assembled on printed wiring boards (also referred to as printed circuit boards). The printed wiring boards typically include a number of through holes for receiving leads or pins from various components which are mounted on the printed wiring board. These component pins extend through the holes and engage printed circuitry within the printed wiring boards which provide numerous electrical connections between the pins of the various components. After being physically mounted on the printed wiring boards, the component pins are typically soldered in the corresponding through holes to provide a reliable electrical connection between the pins and the associated printed circuitry. A printed wiring board on which the components are thus mounted is generally referred to as a printed wiring assembly. It is common during the development of electronic systems that design changes, layout errors, etc. may occur with respect to the printed wiring assemblies. As a result, it is oftentimes necessary to rework or modify printed wiring assemblies even after the components have been assembled and the component pins soldered. Such modifications include cuts, jumpers and so on to change the electrical connections among the component pins within the printed wiring assembly. Unfortunately, such modifications can be difficult to perform particularly when the goal is to isolate electrically one of the component pins from the printed wiring assembly and the printed wiring assembly is populated with high pin count parts such as daughter card connectors or pin grid arrays having on the order of 100 to 300 pins. Further complicating matters is the fact that when the printed wiring assembly utilizes a multi-layer wiring board, most of the printed circuitry is buried within the board. Consequently, it becomes even more difficult to isolate selectively one or more component pins from the printed circuitry.
Previously, reworking a printed wiring assembly to isolate one or more component pins involved removing the solder from each of the component pins in a given component in order to be able to remove the component from the printed wiring assembly. Then it was necessary to drill out the holes of any pins which were to be isolated using an oversize drill. Thereafter, the component needed to be remounted on the printed wiring assembly and all the pins had to be resoldered with the exception of those which were isolated. Unfortunately, this previous reworking technique was very labor intensive. The removal of high pin count components was particularly difficult, risky and time consuming. As an example, the removal of components was risky in that the printed wiring assembly and/or the component itself could be damaged. For instance, lifted pads, cracked plated through hole barrels, and broken component pins could result.
In view of the aforementioned shortcomings associated with previous techniques for reworking printed wiring assemblies, there is a strong need in the art for a rework tool and method for isolating a component pin from the printed wiring assembly in a timely and cost effective manner. In particular, there is a strong need for a rework tool and method which does not require that a component be removed initially from the printed wiring assembly, thereby avoiding the risks of lifted pads, cracked plated through hole barrels, etc.